Synthesis of CdS nanoparticles using different sulfide ion precursors: Formation mechanism and photocatalytic degradation of Acid Blue-29

Cadmium sulphide (CdS) nanoparticles were synthesized by different combinations of chemical precursors using H2S, Na2S and (NH4)2S as sulphide ion sources. The reactions were carried out by a single pot chemical precipitation method under ambient conditions. The X-ray diffraction (XRD) patterns obtained for the synthesized nanoparticles (NPs) were used to determine their crystal structure and the crystallite size. The average particle sizes of the synthesized nanoparticles were determined by transmission electron microscopy, UV–vis spectra and XRD techniques. Electron dispersive spectroscopy and Fourier transform infrared spectroscopy were used to investigate the purity of the synthesized CdS nanoparticles. The smaller particle size for CdS was obtained with Na2S, followed by H2S and (NH4)2S and that the quantization in the band gap was directly in correlation with decreased particle size effects. In addition, mixed phase of wurtzite–zinc blende was synthesized with H2S, while phase pure zinc blende and wurtzite phase was obtained with Na2S and (NH4)2S, respectively. The series of synthesized CdS nanoparticles were exploited for photocatalytic degradation of an organic dye derivative, Acid Blue-29, under visible light and the effect of different precursor combinations on photocatalytic efficiency was analysed. An increase in photocatalytic rate was observed by the decrease in particle size on using different sulfide ion precursors, which can be attributed to the increase in the catalyst surface area, band gap and powerful redox capability. The effect of different sulphide ion sources on the structural and photocatalytic properties was compared and optimized by the above studies.